> Sorry for just telling the idea and not to offering to do it myself. But I
> think this is better than nothing :)

The refactoring browser integration into OB provides that functionality.

1. Left-click on an element of the package you want to search.
2. Click on 'Open Environment | Package'.
3. The opened yellow browser scopes all Refactoring Browser actions to
what you see in this browser.
4. Either use 'Open | Search Code' (for parse tree searches) or 'Open
Environment | Find Sources' (for full text regexp search).

Lukas

-- 
Lukas Renggli
http://www.lukas-renggli.ch